Grease gun with a fluid pressure follower



Dec. 30, 1947. E. w. DAVIS GREASE GUN WITH A FLUID PRESSURE FOLLOWER Filed July 5, 1945 2 Sheets-Sheet l Dec. 30, 1 947. E. w. DAVIS GREASE GUN WITH A FLUID PRESSURE FOLLOWER 2 Sheets-Sheet 2 Filed July 5, 1945 gum? 6/12 /3 J Y Patented Dec. 30, 1947 or-Pics GEE-ESE GUN 'WITH A FLUID PRESSURE FOLLOWER Ernest W. Davis,'River Forest, 111.

Applicationaldly 1945, Serial No. 603,343 2 Claims. ((31.222-262) My invention relates generally to lubricant compressors, and more particularly-tozhand oper- -'ated grease guns of the lever type.

It is an object of my invention to provide .an improved grease gun having means for priming the cylinder by a compressed :air operated follower, the compressed air being supplied by a pump operated in con junction'with the'operation :of the plunger by'whic'h lubricant is 'forced from the cylinder.

A further object is to provide a grease gun having an improved filling means therefor.

A further object is to provide an improved grease gun, the :operation .o'f which will not be 'disadvantageously 'afie'cted'by the presencezof air pockets.

Other objects will appear from the following description, reference being had to 'the accompanying drawings, in which Fig.1 is a centrallongitudinal sectional view of :a grease gun incorporating the invention; and

Fig. 2 is a similar view of a modified form of grease gun, incorporating improved filling means.

Referring "to'Fi'g. l, the grease gun comprises :a generally cylindrical barrel lflzhaving an inte- .gral end 12, the barrel being drawn from sheet metal. The open endofthe barrel lilis threaded in a flanged head rm, which is preferably a -.'die (casting. The head it is provided *with a grease pump cylinder l6 and an =air pumpcylinder -58. .A loose fitting :piston'or plunger 2ll'may have the highpressme plunger'm formed integrallytherewith, and at'itssupperzend is flattened 'for'pivotal cconnectionby 'a :rivet 72A withan operating handle 25, the end-of the valatter bieingfpivoted to the end iota pair of links 28 which in "turn :are pivoted to -a lug 30 forming palt'ofztheEheadcasting I l.

:A cup'washer 3Z2 Iisasecuredcatithe forward face of the piston .29 .by a nut 34 threaded on the plunger .22 :at its juncture with the piston 228. The head may have a port 35 for admitting air to the bore 5 8. The air compressed by theiinward imovement Of the cup leather piston-26,, 3:2,;is discharged past a spring pressed outlet :check valve 3.8 located .in a threaded :boss iii A hollow :follower piston .rod 14.2 is threaded :to :the boss All and projects through the end 12 of the barrel, ein made airtight :by packing as compressed between zagpacking nut lsand the end of :a guide and follower rstop element 38. The latter element is pressed into the end :12 and may be welded :orsoldereid do make it airtight. 'Theae'lezment #38 has a flange 5B which :serves as limit stop .for 5a jollowerzpiston :52. This follower pisiton is preferably molded strum a :suitable sun- 2 thetic rubber compound in the form ofa double cup washer and is-reinforced by aplate 54 having :a cylindricalfian'ge 5B engaging the hollow rod 42 to prevent "tilting of the follower piston 52. The outer end of the hollow rod His-closed by a handle'58 threaded thereon.

Lubricant may flow from :the adjacent-end of the barrel 10 into the high pressure cylinder l6, through an inlet passageway formed in the head casting M, and lubricant discharged from "the high pressure cylinder 16 flows past a spring pressed outlet check valve .62 to the discharge pipe or conduit 64.

Air compressed by the piston :20 is forcedpast the check valve 38 and flows through the hollow rod 42 and ports 66therein to the right-hand end of the barrel l0, thus applying pressure 'to the head l4. At the same time, the hollow rod 42 is unscrewed. The'open end of the barrel is then immersed in a supply of grease and by pulling on the handle 58 the follower piston 52 is drawn upwardly, sucking in a quantity of grease, until further movement is arrested by contact of the follower piston 52 with the flange 50. The barrel may then be screwed back into the head I 4 and the rod 32 screwed on the boss 4.0, it being noted that an airtight seal is effected between the vhollow rod t2 and the boss by virtue of the .provision of a sealing washer 12. The grease gun is then in condition foroperatiomand by relative oscillation of the handle 26 and the barrel l, lubricant will be discharged from the high pressure cylinder by the plunger 22, while at the same time air will be discharged past the check valve 38 into the right-hand end of the barrel [0, thereby to apply pressure to the grease contained in the barrel.

In the modified form of the invention shown in Fig. 2, the barrel 8!] is threaded in the head casting 82, a suitable gasket 84 being provided to seal this joint. The other end of the barrel is closed by a cap 86 threaded thereon, this cap being provided with a packing gland 88 to compress a packing 98 around a follower piston guide rod or tube 92. The head is also provided with an air relief needle valve :94. The hollowrod 9.2 has a handle 96 threaded to the end thereof, and has a cross pin 98 projecting diametrically through it adjacent its inner end. The pin is preferably sealed by solder or the like, so as to prevent the escape of air.

The inner end of the hollow rod 92 is threaded in a check valve fitting I00, which forms the outlet check valve for the air pump, the latter comprising a cylindrical bore I02 in which a plunger I 84 is reciprocable. The plunger I has a cup leather piston I96 secured to the end thereof by a flanged bushing I08 threaded in the piston I04. This bushing I98 has a socket for the receptio of the end of a high pressure plunger III]. wh ch projects through an extension of the high cylinder bore H2. The plunger H0 is secured to the bushing by a pin II3. The connection between the plunger III! and the bushing I08 provides sllfficient play that the plunger may readily align itself with its cylinder H2. To prevent escape of air past the plunger I Ill, there is provided a packing II4. held in place by a packing gland H6.

Lubricant from the left-hand end of the barrel B0 flows through a passageway I I8 to the high pressure grease cylinder H2. A. spring pressed outlet check valve I28 prevents return flow from a rlliiszcharge pipe I2I to the high pressure cylinder The left-hand end of the passageway II8 has a threaded enlargement for the reception of a combined lubricant receiving fitting and shutoff valve I22. This fitting has an externally knurled flange I24 and is provided with a surface I26 for cooperation with the sealing washer I28 of a no..- zle I30 through which lubricant is to be supplied to the gun. The fitting I24 also has an apertured shutoff valve port I34 to close the left-hand end of the passageway H8. The Valve part I 34 is suitably pressed into the fitting I22 and provides a seat for a conical compression spring I35 which holds a ball check valve I38 in closed position. The compressor is operated by a handle I40 pivoted to the plunger I04, as well as joined to the body 82 by pivotal links I42 in the usual manner.

A follower piston I44 is freely slidable upon the tubular guide rod 92 and has a metallic reinforcing member I 46 embedded therein. This member has a pair of arms I48 (only one shown) struck therefrom for bayonet-like locking engagement with the projecting ends of the pin 93.

The follower piston I44 is molded in the form of opposed cup washers and its generally cylindrical surface is relieved at the center, as indicated at I59, so as to assure good sealing contact with the inner surface of the barrel 80. The air pumped past the check valve in the fitting I Iii! is discharged through the hollow tube 92 and ports I52 to the right-hand end of the barrel, thereby to force the follower piston I44 to the left and prime the high pressure cylinder II 2 with grease.

When it is desired to fill the compressor, the air pressure relief valve 94 is opened and the fitting I22 partially unscrewed so as to move the shutoff valve I34 from its seat. The fitting 522 may then make sealed connection with the nozzle I38 and lubricant under pressure supplied through the nozzle used to fill the barrel 80, pressing the follower piston I44 to the right. Movement of the piston to the right is limited by en agement with a suitable annular boss I54 forming part of the cap 86. i

After the grease gun has been filled, thefitting I22 is screwedtightto close the shutofivalve I34 and the air pressure relief valve 94 is closed, whereupon the gun will be in condition for use.

In other respects, the grease gun of Fig. 2 is used in the same manner as that of Fig. 1; that ls, as the handle I40 is oscillated back and forth, grease will not only be discharged past the outlet check valve into the conduit I2I, but at the same time air under pressure will be supplied to the right-hand end of the barrel 80, thereby to place the grease within the barrel under pressure, so that, upon retraction of the plunger IIO from the high pressure cylinder, the latter will be rapidly primed.

When a source of lubricant under pressure is not available for filling the grease gun shown in Fig. 2, it is filled in the following manner: The handle 96 is rotated to unscrew the fitting IIlII from the head 82, and after relieving the air pressure by opening the valve 94, the barrel 80 is unscrewed. The handle 96 is drawn rearwardly to bring the projecting ends of the cross pin 38 against the reinforcing plate I46 of the follower piston and then rotated so as to lock the ends of this pin behind the pair of lugs I48. When this has been done, the open end of the barrel 8!! is immersed in a supply of grease and the handle pulled outwardly to suck in a quantity of grease. If, through inadvertence, or due to the presence of a large air pocket in the supply of grease, a substantial amount of air is admitted to the barrel 80, the operator may push the handle inwardly to discharge such air and whatever grease may have been drawn into the barrel, and make another attempt to fill the barrel solidly with grease. It is for this reason that the bayonet-like detachable connection between the follower and hollow guide rod 92 is necessary.

After the barrel has been filled with grease, the relief valve 94 is closed and the barrel screwed into the head, the guide 92 rotated to disengage the pin 98 from the lugs I48, and the fitting I06 again screwed into the head 82 to provide an airtight path for the flow of air from the air pump to the outer end of the barrel 80.

From the foregoing, it will be clear that I have provided a novel grease gun which is in effect self-priming, which may be easily filled and operated, and in which the presence of pockets of air in the grease will not materially interfere with its satisfactory operation.

While I have shown and described preferred embodiments of my invention, it will be apparent that numerous variations and modifications thereof may be made without departing from the underlying principles of the invention. I therefore desire, by the following claims, to include within the scope of the invention all such variations and modifications by which substantially the results of my invention may be obtained through the use of substantially the same or equivalent means.

I claim:

1. In a lever type grease gun, the combination of a head having a pair of aligned cylinders of different diameters, a two diameter plunger having portions respectively guided in said cylinders, a cup leather secured to the larger diameter portion of the plunger to form a piston and air inlet valve, a barrel secured to the head and having its interior communicating with the smaller diameter cylinder, a follower piston freely mov-v able in the barrel, a hollow guide rod for said follower piston, said guide rod being secured to said head, a check valved passageway connecting the larger of said cylinders with said guide rod, said guide rod having an opening for conducting air to the end of said barrel remote from the head, and manually operable means for reciprocating said plunger comprising a handle pivoted intermediate its ends to the outer end of the plunger and a link having its ends pivotally connected to the end of the handle and to the head respectively.

2. In a hand operated lubricant compressor, the combination of a head having a large cylinder and a small cylinder formed therein, said cylinders being in substantial alignment and adjacent one another, a plunger having a small diameter portion operating as a piston in the small cylinder and having a large diameter portion guided in the large cylinder, an air pump comprising a flexible cup piston secured to the lrrge diameter portion of the plunger, and an outlet check valve; a barrel detachably secured to the head and communicating with the small cylinder therein, a follower piston freely movable within the barrel, a hollow rod for guiding said follower piston, said rod being secured to the head 6 and forming a passageway for the discharge of air therefrom to the end of the barrel remote from the head, an outlet check valve for the small cylinder, a handle pivoted to said 1:1unger, and a link pivotally connected to the handle and to the body.

ERNEST W. DAVIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

